P{TransTimer} is an enhancer trap construct that can be used to study endogenous transcriptional dynamics. The enhancer trap sequence consists of the Drosophila synthetic core promoter (DSCP) promoter followed by a multicistronic reporter in which a destabilized form of sfGFP (sfGFP that is tagged at C-terminal end with the Tag:PEST(mOdc) destabilization sequence) is separated from TagRFP by a self-cleaving 2A motif. Both coding sequences are tagged at the N-terminal end with a Tag:NLS(SV40-largeT) nuclear localization signal. The destabilized sfGFP protein is also tagged at the C-terminal end with 3xTag:MYC and the TagRFP protein is tagged at the C-terminal end with 3xTag:HA. The transgene contains a number of translation enhancing elements: a short 87 bp intervening sequence (IVS) from Mhc to promote mRNA export to the cytoplasm, a 21bp synthetic AT-rich sequence (Syn21) to promote translational initiation and an efficient p10 polyadenylation signal.